Delivery of medical devices

Abstract

A stent delivery system can include a core member, an introducer sheath, and a microcatheter. The core member can have a distal segment. The stent engagement member can have a generally tubular body positioned about the core member distal segment and can be rotatably coupled to the core member. The engagement member can include an inner layer that has a first durometer and an outer layer that has a second durometer less than the first durometer. The stent can extend along the core member distal segment such that an inner surface of the stent is engaged by the engagement member outer layer for facilitating rotation of the stent relative to the core member.

The invention claimed is: 
     
       1. A stent delivery system, comprising:
 a core member having:
 a first section comprising a solid wire having a proximal grip region; and 
 a second section distal to the first section, the second section comprising a tubular member having a length of at least 50 cm and a bending stiffness per unit length that is less than a bending stiffness per unit length of the first section; and 
 a third section comprising a solid wire distal to the second section; 
 
 an implant carried by the third section of the core member; and 
 an introducer sheath having a proximal end, a distal end, and a lumen for receiving the core member therein such that, in a first configuration, implant is disposed within the lumen and the proximal grip region of the core member extends proximal to a proximal end of the introducer sheath, and in a second configuration, the core member is advanced distally such that the second section and the third section are entirely distal to the distal end of the introducer sheath and the proximal grip region extends proximal to the proximal end of the introducer sheath, the introducer sheath having a length of at least about 80 cm, the distal end of the introducer sheath configured to connect to a proximal hub of a microcatheter for transitioning the core member and the implant disposed within the introducer sheath out of the distal end of the introducer sheath and into the microcatheter through the proximal hub, wherein the distal end of the introducer sheath is configured to be detachable from the microcatheter hub while the microcatheter remains within a patient. 
 
     
     
       2. The system of  claim 1 , wherein the sheath length is equal to or greater than a length of the core member second section. 
     
     
       3. The system of  claim 1 , wherein the first section has a substantially constant bending stiffness per unit length. 
     
     
       4. The system of  claim 1 , wherein the sheath length is between about 80 cm and about 150 cm. 
     
     
       5. The system of  claim 4 , wherein the sheath length is about 106 cm. 
     
     
       6. The system of  claim 1 , wherein the core member comprises a marker visible through the introducer sheath. 
     
     
       7. The system of  claim 6 , wherein the marker is disposed along the core member in the first section thereof. 
     
     
       8. The system of  claim 6 , wherein the introducer sheath comprises titanium dioxide. 
     
     
       9. The system of  claim 1 , wherein at least a portion of the tubular member comprises a spiral cut. 
     
     
       10. The system of  claim 9 , wherein the spiral cut extends along about 60 cm to about 100 cm of a length of the second section. 
     
     
       11. The system of  claim 10 , wherein the spiral cut extends along about 86 cm of the length of the second section. 
     
     
       12. A stent delivery system, comprising:
 a core member having (i) a stiff section having a first bending stiffness, (ii) a soft section distal to the stiff section and having a length of at least 50 cm and a second bending stiffness that is less than the first bending stiffness, the second bending stiffness varying spatially along the soft section, and (iii) a distal section distal to the soft section; 
 an implant carried by the distal section of the core member; and 
 an introducer sheath having a bending stiffness that is less than the first bending stiffness, the introducer sheath having a lumen, a distal end, and a length of at least about 80 cm, 
 wherein, in a first configuration, the introducer sheath covers the soft section and the distal section of the core member while a proximal grip portion of the core member extends proximally of a proximal end of the introducer sheath, and, in a second configuration, the core member is advanced distally such that the entirety of the soft section of the distal section are distal to the distal end of the introducer sheath and the proximal grip region extends proximal to the proximal end of the introducer sheath, 
 wherein the distal end of the introducer sheath is configured to connect to a proximal hub of a microcatheter for transitioning the core member and the implant disposed in the introducer sheath out of the distal end of the introducer sheath and into a lumen of the microcatheter, and wherein the distal end of the introducer sheath is configured to be detachable from the proximal hub of the microcatheter after the implant is transitioned into the microcatheter and while the microcatheter remains in the patient, 
 wherein the proximal portion of the core member comprises a marker visible through a sidewall of the introducer sheath and positioned such that when the core member is advanced through the introducer sheath to a position with the marker disposed adjacent the distal end of the introducer sheath, the implant carried by the distal portion of the core member is positioned adjacent to a distal end of the microcatheter. 
 
     
     
       13. The system of  claim 12 , wherein the bending stiffness of the stiff section is substantially constant. 
     
     
       14. The system of  claim 12 , wherein the stiff section is proximal to the soft section. 
     
     
       15. The system of  claim 12 , wherein the core member comprises a hollow tubular member in the soft section. 
     
     
       16. The system of  claim 15 , wherein at least a portion of the hollow tubular member comprises a spiral cut. 
     
     
       17. The system of  claim 12 , wherein the sheath length is between about 80 cm and about 150 cm. 
     
     
       18. The system of  claim 12 , wherein the sheath length is about 106 cm.